[llvm-dev] Get the address of ConstantDataArray

Sam Elliott via llvm-dev llvm-dev at lists.llvm.org
Thu Nov 21 05:36:45 PST 2019

Pointer arithmetic in LLVM is done using the getelementptr (GEP) instruction.

There’s a document which explains them [1], but I found this tutorial [2] from EuroLLVM 2019 was the first resource to explain it in a way I understood.

I hope this helps!


[1]: https://llvm.org/docs/GetElementPtr.html
[2]: https://www.youtube.com/watch?v=m8G_S5LwlTo

> On 20 Nov 2019, at 12:24 pm, Alberto Barbaro via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> Hi all,
> I have a global array declared as: table = internal constant [8 x [256 x i32]] ...
> At the moment I'm able to get the reference to table using Constant* g_var = cast<GlobalVariable>(I.getOperand(0))->getInitializer(); ( please consider I to be a GetElementPtrInst object ).
> Now I would like to understand how to get the address of table[2][3], for instance, considering that I have the g_var variable.
> In addition, I was able to access to the value table[2][3] so for me would be also OK to have the address of that specific value once I already have access to the value.
> Thanks
> Alberto
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Sam Elliott
Software Developer - LLVM

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